acute lymphocytic leukemia (ALL) - a rapidly progressing cancer of the blood in which too many immature (not fully formed) lymphocytes, a type of white blood cell, are found in the bone marrow, blood, spleen, liver, and other organs.

acute myelogenous leukemia (AML) - a rapidly progressing cancer of the blood in which too many immature (not fully formed) granulocytes, a type of white blood cell, are found in the bone marrow and blood.

allogeneic bone marrow transplantation - a procedure in which a person receives stem cells from a compatible donor.

blood - the life-maintaining fluid which is made up of plasma, red blood cells (erythrocytes), white blood cells (leukocytes), and platelets; blood circulates through the body's heart, arteries, veins, and capillaries; it carries away waste matter and carbon dioxide, and brings nourishment, electrolytes, hormones, vitamins, antibodies, heat, and oxygen to the tissues.

blood banking - the process that takes place in the laboratory to ensure that donated blood, or blood products, are safe before they are used in blood transfusions and other medical procedures. Blood banking includes typing the blood for transfusion and testing for infectious diseases.

blood plasma - the fluid part of blood that contains nutrients, glucose, proteins, minerals, enzymes, and other substances.

bone marrow aspiration and biopsy - the marrow may be removed by aspiration or a needle biopsy under local anesthesia. In aspiration biopsy, a fluid specimen is removed from the bone marrow. In a needle biopsy, marrow cells (not fluid) are removed. These methods are often used together.

bone marrow transplantation (BMT) - the transfusion of healthy bone marrow cells into a person after their own unhealthy bone marrow has been eliminated.

chronic lymphocytic leukemia (CLL) - a slowly progressing cancer of the blood in which too many lymphocytes, a type of white blood cell, are produced by the bone marrow and by organs of the lymph system.

chronic myelogenous leukemia (CML) - a slowly progressing cancer of the blood in which too many white blood cells are produced in the bone marrow.

coagulation disorders - problems with either the inability for blood to clot properly, resulting in excessive bleeding, or excessive clotting leading to obstruction of veins and arteries (thrombosis).

complete blood count (CBC) - a measurement of size, number, and maturity of the different blood cells in a specific volume of blood.

computed tomography scan (also called a CT or CAT scan) - a diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce horizontal, or axial images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.

factor - a protein in the blood that is needed to form the blood clot.

factor V Leiden - an inherited mutation (change in a gene) in factor V which increases a personï¿½s risk for venous thrombosis.

folate deficiency - the lack of folic acid (one of the B vitamins) in the blood.

folic acid - a nutrient found in some green leafy vegetables, nuts, beans, citrus fruits, fortified breakfast cereals, and some vitamin supplements. Folic acid can help reduce the risk of birth defects of the brain and spinal cord.

hematocrit - the measurement of the percentage of red blood cells found in a specific volume of blood.

hematologist - a physician who specializes in the functions and disorders of the blood.

hematology - the scientific study of blood and blood-forming tissues.

hematopoiesis - the process of producing and developing new blood cells.

hemochromatosis (Also called iron overload disease.) - a metabolic disorder that causes increased absorption of iron, which is deposited in the body tissues and organs. The iron accumulates in the body where it may become toxic and cause damage.

hemoglobin - substance in the red blood cells that supplies oxygen to the cells of the body.

hemolytic anemia - one type of anemia in which the red blood cells are destroyed prematurely.

hemophilia (Also called coagulation disorder.) - an inherited bleeding disorder caused by low levels, or absence of, a blood protein that is essential for clotting; hemophilia A is caused by a lack of the blood clotting protein factor VIII; hemophilia B is caused by a deficiency of factor IX.

Hodgkin disease - A type of lymphoma, a cancer in the lymphatic system; a rare disease, accounting for less than 1 percent of all cases of cancer in the US, and occurs most often in people between the ages of 15 and 34, and in people over age 55. Hodgkin disease causes the cells in the lymphatic system to abnormally reproduce, eventually making the body less able to fight infection. Steady enlargement of lymph glands, spleen, and other lymphatic tissue occurs.

idiopathic thrombocytopenic purpura - a blood disorder characterized by an abnormal decrease in the number of blood platelets, which results in internal bleeding. There are two forms of idiopathic thrombocytopenic purpura: acute thrombocytopenic purpura and chronic thrombocytopenic purpura.

iron-deficiency anemia - the most common type of anemia. It is characterized by a lack of iron in the blood, which is necessary to make hemoglobin.

leukapheresis - a procedure to remove excess lymphocytes from the body.

leukemia - a cancer of the blood-forming tissue. Leukemic cells look different than normal cells and do not function properly.

lumbar puncture (Also called spinal tap.) - a special needle is placed into the lower back, into the spinal canal. This is the area around the spinal cord. The pressure in the spinal canal and brain can then be measured. A small amount of cerebral spinal fluid (CSF) can be removed and sent for testing to determine if there is an infection or other problems. CSF is the fluid that bathes the brain and spinal cord.

lymph - part of the lymphatic system; a thin, clear fluid that circulates through the lymphatic vessels and carries blood cells that fight infection and disease.

lymph node biopsy - a procedure performed to remove tissue or cells from the body for examination under a microscope.

lymph nodes - part of the lymphatic system; bean-shaped organs, found in the underarm, groin, neck, and abdomen, that act as filters for the lymph fluid as it passes through them.

lymph vessels - part of the lymphatic system; thin tubes that carry lymph fluid throughout the body.

lymphangiograms - x-rays of the lymphatic system.

lymphatic system - part of the immune system; includes lymph, ducts, organs, lymph vessels, lymphocytes, and lymph nodes, whose function is to produce and carry white blood cells to fight disease and infection.

lymphocytes - part of the lymphatic system; white blood cells that fight infection and disease.

lymphocytic leukemia - a type of leukemia in which the cancer develops in the lymphocytes (lymphoid cells).

magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.

megaloblastic anemia - a rare blood disorder caused by a deficiency of either folate (a B vitamin) or Vitamin B-12, resulting in an inadequate amount of red blood cells produced.

myelogenous leukemia - a type of leukemia in which the cancer develops in the granulocytes or monocytes (myeloid cells).

myeloproliferative disorders - diseases in which the bone marrow produces too many of one of the three types of blood cells: red blood cells, which carry oxygen to all the tissues in the body; white blood cells, which fight infection; and platelets, which makes blood clot.

non-Hodgkin lymphoma - a type of lymphoma, a cancer in the lymphatic system; causes the cells in the lymphatic system to abnormally reproduce, eventually causing tumors to grow. Non-Hodgkin lymphoma cells can also spread to other organs.

radiation therapy (Also called radiotherapy.) - treatment with high-energy rays (such as x-rays or gamma rays) to kill cancer cells; may be by external radiation or by internal radiation from radioactive materials placed directly in or near the tumor.

red blood cells (Also called RBCs or erythrocytes.) - main function is to transport oxygen to all the tissues in the body.

spinal tap (Also called lumbar puncture.) - a special needle is placed into the lower back, into the spinal canal. This is the area around the spinal cord. The pressure in the spinal canal and brain can then be measured. A small amount of cerebral spinal fluid (CSF) can be removed and sent for testing to determine if there is an infection or other problems. CSF is the fluid that bathes the brain and spinal cord.

splenectomy - surgery to remove the spleen.

stem cells - the blood cells that produce other blood cells. It is the stem cells that are needed in bone marrow transplantation.

thalassemia - an inherited blood disorder in which the chains of the hemoglobin (a type of protein in red blood cells that carries oxygen to the tissues) molecule are abnormal; alpha thalassemia is where a mutation occurs in the alpha chain, while beta thalassemia is where the mutation occurs in the beta chain; signs and symptoms of thalassemias vary from mild (little to no symptoms) to severe (life threatening).

ultrasound (Also called sonography.) - a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.

umbilical cord blood transplant - a procedure in which stem cells are taken from an umbilical cord immediately after delivery of an infant.